Dining in Manhattan: most of us spend more on holiday. Photograph: Ambient Images Inc./Alamy

We purchased a Post Office Travel Money Card to avoid taking large amounts of cash on holiday in the US. Unfortunately, we had quite a few embarrassing moments when the card was declined in stores and restaurants. After a balance check, we established that we had plenty of funds, but still the transactions were declined.

It was also costly as I had to use a credit card to make the payments, which in turn incurred a charge along with a poor exchange rate. As a result, we returned with in excess of $500 on the card which we had been unable to withdraw. When I tried to get the balance refunded in sterling I was told the rate they would buy back at was $1.82 to the pound. The failure of their card to work as claimed on their website will mean we only get around £280 back out of the remaining £350 we put on it. JR, Rochdale

Yours is one of many similar complaints I receive after the holiday season. The problem is that the Money Card has a daily transaction limit to guard against fraud. The terms and conditions warn of this, but the Post Office won't disclose what this limit is for "security reasons". A spokeswoman says: "Given the volume of transaction attempts in a short space of time, a risk rule was triggered on the account which resulted in them being declined. In line with most other banks and card issuers, we have rules in place to highlight untypical behaviour on the account."

The trouble is most of us do spend more on holiday and the Money Card, being temporary, is not in our possession long enough for "typical" behaviour to be recorded. In future, if you're likely to be shelling out frequently, you're better off using the Money Card as back-up and relying on your credit card for bigger purchases.

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